Methods and apparatus to measure and analyze vibration signatures

ABSTRACT

Methods and apparatus to measure and analyze vibration signatures are disclosed. In some examples, a meter is provided comprising a waveform generator to generate a waveform based on first distance measurements of an object. In some examples, the meter includes a waveform generator to determine a first vibration characteristic of the object based on the waveform. In some examples, the meter includes a comparator to compare the first vibration characteristic to a signature vibration characteristic of the object, the signature vibration characteristic of the object indicative of normal characteristics of the object. In some examples, the meter includes a reporter to, in response to determining the first vibration characteristic does not match the signature vibration characteristic, generate an alert.

RELATED APPLICATION

This patent claims the benefit of U.S. Provisional Application Ser. No.62/205,821, which was filed on Aug. 17, 2015, and is hereby incorporatedherein by reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure relates generally to object detection and measurement,and, more particularly, to methods and apparatus to measure and analyzevibration signatures.

BACKGROUND

In recent years, vibration analysis has been used to determine detailsabout measured objects, such as, for example, faults or degradation,that would otherwise go undetected until an actual fault. Often,vibration analysis can detect defects preemptively, before the defectscause a major problem. To provide such vibration analysis, meters havebeen placed on objects to detect vibrations by allowing the meters tooscillate along with the objects. Additionally, probes have been used todetect ultrasonic sound waves emitted from objects and convert theultrasonic waves into the audible and/or visual domain.

SUMMARY

Methods and apparatus to measure and analyze vibration signatures aredisclosed. In some examples, a meter is provided comprising a waveformgenerator to generate a waveform based on first distance measurements ofan object. In some examples, the meter includes a waveform generator todetermine a first vibration characteristic of the object based on thewaveform. In some examples, the meter includes a comparator to comparethe first vibration characteristic to a signature vibrationcharacteristic of the object, the signature vibration characteristic ofthe object indicative of normal characteristics of the object. In someexamples, the meter includes a reporter to, in response to determiningthe first vibration characteristic does not match the signaturevibration characteristic, generate an alert.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are diagrams illustrating an example environment includingan example controller in communication with an example ultrasonictransducer to obtain distance measurements of an object.

FIG. 2 is a diagram illustrating an example environment including anexample controller in communication with an example ultrasonictransmitter and an example ultrasonic receiver to obtain distancemeasurements of an object.

FIG. 3 is a block diagram illustrating the example controller of FIGS.1A-1B.

FIG. 4 is a diagram illustrating example interactions between theexample transducer and example object of FIGS. 1A-1B.

FIGS. 5-6 are flow charts illustrating example instructions to implementthe example controller of FIGS. 1A-1B and 3.

FIG. 7 is a flow chart illustrating example instructions to implement anexample filter and an example waveform analyzer of FIG. 3.

FIG. 8 is a block diagram of an example processor platform to implementthe example flow charts of FIGS. 5-7.

DETAILED DESCRIPTION

Oscillating objects display particular characteristics that can bemeasured and analyzed. In order to measure and analyze the vibrations ofobjects, previous methods have involved either installing a meter on theobject to be measured or detecting ultrasonic sound waves emitted fromthe object that are otherwise unheard (e.g., due to ultrasonic wavesbeing outside the audible domain).

On-object meters are often implemented using accelerometers, whichdetect gravitational forces (e.g., redistribution of weight, shock,falling, etc.). These on-object meters must be mounted on the device tobe measured, because the accelerometer detects gravitational forces asapplied to the accelerometer (e.g., if the object moves, theaccelerometer will only move, and thus report such movement, if it isattached to the object). Because such meters need to be mounted onobjects to measure the same, the meters are subject to substantial wear,varying temperatures, contaminants, moving parts, and other volatileenvironments. Accordingly, such devices require frequent replacement,repair, and/or configuration.

Additionally, it is often difficult to report the measurements acquiredby on-object meters, especially meters that are positioned on movingparts (e.g., a motor). Thus, the on-device meter has to wirelesslytransmit data, be wired in such a way to avoid severing the wiredconnection, and/or be removed for such reporting purposes. Any wirelessdevices and/or complex wiring is also subject to the substantial wear,varying temperatures, contaminants, moving parts, and other volatileenvironments as the meters themselves.

The detection of ultrasonic sound waves emitted from objects ofteninvolves a probe attached to an audio producing device (e.g.,headphones, speakers, etc.) to convert inaudible sound waves intoaudible sound. However, often the only way to receive a precise readingrequires the probe to be in direct contact with the object and in thesame orientation as the emitted ultrasonic waves. Further, ultrasonicsound waves emitted from the object merely provide an associationbetween a particular audible sound with a particular operation. Suchprobing devices do not provide a high level of detail regarding thecharacteristics of a vibrating object (e.g., the converted ultrasonicsound waves do not establish a vibration frequency, displacement, phase,etc.).

Additionally, ultrasonic waves are subject to noise (e.g., interference)from other related or unrelated sound waves. Therefore, the soundconverted by the probe and audio producing devices is often not even atrue representation of only the ultrasonic sound waves emitted from theobject. The comparison of the level of a desired signal to the level ofbackground noise is called the signal to noise ratio (“SNR”) and isoften expressed in decibels (e.g., dB). A high SNR (e.g., greater than 0dB) indicates more signal than noise, while a low SNR (e.g., less than 0dB) indicates more noise than signal. To obtain a higher SNR, filtersare used to remove noise or other unwanted signals. Noise can affect theamplitude, frequency, and/or phase of a signal and specific filters arerequired to correct each type of unwanted artifact. When probing forsound waves emitted from objects, it is often difficult to distinguishnoise from signal, and therefore, difficult to determine what filteringarrangement to use.

The example methods and apparatus of the present disclosure, incontrast, provide off-device measurement using ultrasonic transducers(e.g., transmitters, receivers, transceivers, etc.) to measure variancesin the distance between the ultrasonic transducers and the object to bemeasured to determine vibration characteristics of the object. Theexample methods and apparatus generate ultrasonic waves with particularknown characteristics (e.g., frequency) to measure variances in distanceof an oscillating object, which provide higher levels of detail than theconversion of ultrasonic sound waves emitted from objects into theaudible and/or visual domains.

FIGS. 1A-1B are diagrams illustrating an example environment 100including an example controller 102 in communication with an exampleultrasonic transducer 104. In the illustrated example, the exampleultrasonic transducer 104 is a transceiver that is capable of sendingand receiving ultrasonic waves. The example ultrasonic transducer 104converts electrical signals (e.g., voltage, current, etc.) to ultrasonicwaves when electrical signals are applied to a piezoelectric sensorwithin the example ultrasonic transducer 104. The electrical signalscauses the piezoelectric sensor to oscillate and emit ultrasonic waves.This process is reversed when the example ultrasonic transducer 104receives ultrasonic waves. The received ultrasonic waves cause thepiezoelectric sensor to oscillate and generate electrical signals. Insome examples, transmission and reception of ultrasonic waves (e.g.,sampling) may interfere with each other (e.g., oscillation due totransmission is still occurring when ultrasonic waves are received,oscillation due to reception is still occurring when ultrasonic wavesare transmitted, etc.) The example methods and apparatus disclosedherein compensate for such interferences by transmitting phase shiftedultrasonic waves at lower frequencies when the ultrasonic transducer 104is oscillating from a previous transmission and/or reception ofultrasonic waves. In the illustrated example, the example ultrasonictransducer 104 creates ultrasonic waves with a frequency of 400kilohertz (“kHz”). Additionally and/or alternatively, ultrasonic waveshaving different frequencies may be used (e.g., 40 kHz, 100 kHz, etc.).

In FIG. 1A, the example ultrasonic transducer 104 sends exampleultrasonic waves 106 towards an example object 108 to obtain a firstdistance measurement of the example object 108. The example ultrasonicwaves 106 travel from the example ultrasonic transducer 104 through amedium, such as, for example, the air, towards the example object 108.Additionally or alternatively, the example ultrasonic transducer 104 maysend ultrasonic waves through other mediums, such as liquids. Theexample ultrasonic waves 106 reflect off the example object 108 andtravel back towards the example ultrasonic transducer 104. The examplecontroller 102 controls when the example ultrasonic transducer 104 sendsthe example ultrasonic waves 106, recognizes when the example ultrasonictransducer 104 receives an echo of the example ultrasonic waves 106(e.g., the example ultrasonic waves 106 returning from reflecting off anobject, such as the example object 108), and determines the time betweenthe sending and the receiving of the ultrasonic waves 106 (e.g., time offlight). The example controller 102 determines the distance between theexample transducer 104 and the example object 108 based on the time offlight of the example ultrasonic waves 106 and the speed of sound (e.g.,343 meters per second (m/s)). In the illustrated example of FIG. 1A, theexample controller 102 determines that the example object 108 is a firstdistance 110 away from the example ultrasonic transducer 104.

In FIG. 1B, the example ultrasonic transducer 104 sends exampleultrasonic waves 112 towards the example object 108 to obtain a seconddistance measurement of the example object 108. In the illustratedexample, the example controller 102 determines that the example object108 is a second distance 114 away from the example ultrasonic transducer104. The example controller 102 further determines that the seconddistance 114 is greater than the first distance 110 by a third distance116. In some examples, when the example controller 102 determines theexample object 108 oscillates between the first distance 110 and thesecond distance 114, the example controller 102 determines that theexample object 108 is vibrating. The example controller 102 furtherdetermines vibration characteristics (e.g., frequency, amplitude, phase,etc.) of the example object 108, as further discussed herein. Forexample, the example controller 102 determines that the example thirddistance 116 is the total displacement of the example object 108. Theexample controller 102 then determines that half the example thirddistance 116 (e.g., half the total displacement) is the amplitude of theexample object 108 from rest. Alternatively, the first distance 110 mayrepresent the example object 108 at rest and the example second distance114 may represent the maximum distance the example object 108 is fromthe example ultrasonic transducer 104. In such examples, the differencebetween the example second distance 114 and the example first distance110 (e.g., the example third distance 116) is the actual amplitude ofthe example object 108.

While the examples of FIGS. 1A-1B illustrate one ultrasonic transducer,other numbers of ultrasonic transducers, ultrasonic transmitters, and/orultrasonic receivers may be used in replace of or in conjunction withthe example ultrasonic transducer 104. In some examples, multipleultrasonic transducers are used to measure multiple surfaces of theexample object 108 (e.g., a first ultrasonic transducer measures a firstsurface and a second ultrasonic transducer measures a second surface).

FIG. 2 is a diagram illustrating an example environment 200 including anexample controller 202 in communication with an example ultrasonictransmitter 204 and an example ultrasonic receiver 206 to obtaindistance measurements of an object 208. In some examples, the examplecontroller 202 is similar to the example controller 102 in FIGS. 1A-1B.In the illustrated example, the example ultrasonic transmitter 204 sendsexample ultrasonic waves 210 towards the example object 208 in a firstdirection. The example ultrasonic waves 210 reflect off the exampleobject 208 and form example reflected waves 212. The example ultrasonicreceiver 206 receives the example reflected waves 212. The examplecontroller 202 determines the time between the transmission of theexample ultrasonic waves 210 and the receipt of the example reflectedwaves 212 to obtain a first distance measurement 214 of the exampleobject 208. Additionally or alternatively, the example ultrasonictransmitter 204 and/or the example ultrasonic receiver 206 may beultrasonic transceivers that both transmit and receive ultrasonic waves.

In the illustrated example, an ultrasonic transducer 216 incommunication with the example controller 202 sends example ultrasonicwaves 218 towards the example object 208 in a second direction. Theexample ultrasonic waves 218 reflect off the example object 208 andreturn to the example ultrasonic transducer 216. The example controller202 determines the time between the transmission and receipt of theexample ultrasonic waves 218 to obtain a second distance measurement 220of the example object 208. Thus, in the illustrated example, the examplecontroller 202 determines variations in distance (e.g., vibration) inthe first and second directions.

Accordingly, the example methods and apparatus disclosed hereindetermine vibration characteristics of the example object 108, 208 whilebeing disposed a distance away from the example object 108, 208. Thusthe example controller 102, 202 and the example ultrasonic transducer104, the example ultrasonic transmitter 204, the example ultrasonicreceiver 206, and/or the example ultrasonic transducer 216 are notsubject to the same substantial wear, contaminants, moving parts, andother volatile environments to which on-device meters are subjected.Additionally, the example methods and apparatus save power by uniformlysampling with low power ultrasonic transmitters, receivers, and/ortransducers.

FIG. 3 is a block diagram illustrating the example controller 102 ofFIGS. 1A-1B. In some examples, the example controller 102 embodies or isin communication with one or more additional components including, forexample, a low noise amplifier (“LNA”), an analog front end (“AFE”), ananalog to digital converter (“ADC”), a power supply, a bandpass filtercircuit, a time to digital converter (“TDC”), a Hilbert transform finiteimpulse response (“FIR”) filter, or other like components. In someexamples, ultrasonic wave characteristics are affected by temperature,local atmospheric variations, air conditioning, humidity, air density,etc. The example methods and apparatus compensate for such variances. Insuch examples, the example controller 102 embodies or in communicationwith a temperature sensor to provide start and stop signals proportionalto the temperature sensed. Additionally or alternatively, the examplepulse generator 300 may adapt the sampling frequency of the exampleultrasonic transducer 104 in response to variations in the environment.

The example controller 102 includes an example pulse generator 300, anexample waveform generator 302, an example filter 304, an examplewaveform analyzer 306, an example comparator 308, an example signatureassociator 310, an example characteristic database 312, and an examplereporter 314, all in communication via an example bus 316. The examplebus 316 enables communication between the example controller 102 and theexample ultrasonic transducer 104.

The example pulse generator 300 triggers the sending of ultrasonic waves(e.g., example ultrasonic waves 106, 112) from the example ultrasonictransducer 104. For example, the example pulse generator 300 triggers aburst of pulses (e.g., three) that instruct the example ultrasonictransducer to send the same number of ultrasonic waves (e.g., three)towards the example object 108. The example pulse generator 300 cantrigger any number of pulses within a burst as necessary to obtainaccurate readings of the example object 108. Additionally, the examplepulse generator 300 controls the frequency at which each burst of pulsesis sent (e.g., the sampling frequency fs). In the illustrated example,the example pulse generator 300 samples at a frequency fs of 120 Hz.Additionally or alternatively, the example pulse generator 300 maysample at alternate frequencies (e.g., 60 Hz, 240 Hz, etc.). To detectthe frequency at which an object is vibrating, the example pulsegenerator 300 samples at a frequency at least twice as fast as theexample object 108 is suspected to be vibrating (e.g., samplingfrequency of 120 Hz for an object vibrating at 60 Hz). In some examples,the example pulse generator 300 adapts the sampling frequency fs due totemperature variations, transmission and reception interference, orother conditions.

The example waveform generator 302 creates or otherwise generates awaveform based on a plurality of sample points (e.g., sample data)acquired by the example ultrasonic transducer 104 (FIGS. 1A-1B). Forexample, each pulse sent by the example ultrasonic transducer 104returns information regarding the distance of the example object 108 ata particular point in time (e.g., a sample point). The example waveformgenerator 302 utilizes a plurality of distance data at different samplepoints (e.g., points in time) to generate a waveform representing thevibration of the example object 108. According to Fourier series, theexample waveform generator 302 can define the waveform as a summation ofsine and/or cosine waves, which simplifies analysis of the waveform. Insome examples, storing all data corresponding to each sample point maylead to memory overflow, overwriting data, loss of data, or otherconsequences. Therefore, the example waveform generator 302 generatesthe waveform based on successive uniform sampling of the data acquiredby the example ultrasonic transducer 104.

Example waveforms that the example waveform generator 302 createsinclude waveforms in the sample domain (e.g., distance (y-axis) measuredby each pulse (x-axis)), the frequency domain (e.g., normalizedamplitude (y-axis) by frequency (x-axis) (e.g., fast Fourier transformof the sample domain)), phase domain (e.g., phase (y-axis) by time(x-axis)), or the time domain (e.g., distance (y-axis) by time (x-axis),velocity (y-axis) by time (x-axis), acceleration (y-axis) by time(x-axis), etc.). Initially, the example waveform generator 302 creates avibration displacement waveform in the sample domain (e.g., distance(x-axis) by each pulse (x-axis)).

The highest frequency waveform that the example waveform generator 302can create is based the Nyquist frequency. The Nyquist frequency is halfof the sampling frequency fs in a discrete signal processing system. Toreconstruct an original waveform with a frequency f, the Nyquistfrequency (e.g., fs/2) has to be greater than the absolute value of thewaveform frequency f (e.g., fs/2>|f|). Otherwise, an alias waveform willbe created instead of the original waveform. Aliasing is to be avoided,as incorrect vibration characteristics may be recorded if an aliaswaveform is constructed instead of the original waveform.

The example filter 304 receives the created waveform from the examplewaveform generator 302. In the illustrated example, the example filter304 applies one or more filters to the created waveform to resolveultrasonic signals from noise. In some examples, the example filter 304applies a bandpass filter to the generated waveform to keep certainfrequencies (e.g., within a passband) and exclude other frequencies. Anexample bandpass filter is a resistor-inductor-capacitor (RLC) circuit.Alternatively, combining a high pass filter (e.g., a capacitor connectedto a load and a resister in parallel) to exclude low frequencies and alow pass filter (e.g., a resister connected to a load and capacitor inparallel) to exclude high frequencies achieves the same result of abandpass filter. For example, a bandpass filter centered at 400 kHzapplied to the created waveform would keep data related to the exampleultrasonic transducer 104, which operates at 400 kHz, while removingother frequencies, such as 4 kHz, which may be background noise thatwould otherwise disrupt data from the example ultrasonic transducer 104.

In some examples, the example filter 304 applies a Hilbert transform FIRfilter to the generated waveform to shift the phase of the generatedwaveform. For example, by taking advantage of the corollary that sin(−ωt+θ) is indistinguishable from sin (ωt−θ+π) and cos (−ωt+θ) isindistinguishable from cos (ωt−θ) and applying the Hilbert transform FIRfilter, the example filter 304 can represent the generated waveform injust positive frequencies (e.g., ω). In the illustrated example, theexample filter 304 distinguishes the original waveform from aliases byapplying both a bandpass filter and a Hilbert transform FIR filter tomodulate the amplitude and phase of the signal received by the exampleultrasonic transducer 104. In the illustrated example, the examplefilter 304 outputs the resolved waveform to the example waveformanalyzer 306.

The example waveform analyzer 306 determines characteristics of theexample object 108 from the resolved waveform from the example filter304. Example characteristics of the resolved waveform include Height(e.g., displacement of the example object 108), Amplitude (e.g.,displacement of the example object 108 from rest), Frequency (e.g.,cycles per second), Velocity (e.g., distance per second), orAcceleration (e.g., distance per second squared).

In the illustrated example, the example waveform analyzer 306 applies ahigh resolution algorithm to the filtered displacement waveform (e.g.,amplitude by sample) to obtain subwavelength resolution (e.g.,resolution at a dimension smaller than the wavelength). The examplefilter 304 envelopes the generated waveform, performs phase linearregression on a plurality of points around a first time, and determinessubwavelength resolution based on the zero crossing nearest the firsttime. To envelope the generated waveform, the example waveform analyzer306 inputs the bandpass filtered waveform through an envelope detectorcircuit (e.g., a diode connected to a capacitor, a resistor, and a loadin parallel). The envelope effectively outlines at least one of an upperor lower bound of the waveform to generalize the amplitude of thewaveform. As discussed herein, the example methods and apparatus utilizean upper bounded envelope, however, the example disclosed methods andapparatus may alternatively use a lower bounded envelope withoutdeparting from the scope of the present disclosure.

The waveform analyzer 306 determines a first time wherein the envelopedamplitude is greater than half of the maximum enveloped amplitude. Thewaveform analyzer 306 further identifies a plurality of sample points(e.g., 10) of the waveform that surround the first time. The waveformanalyzer 306 performs linear regression on the plurality of samplepoints (e.g., determining the best fitting line amongst the plurality ofsample points) in the phase domain (e.g., phase by time) and identifiesa zero crossing nearest to the first time. From the nearest zerocrossing, the example waveform analyzer 306 identifies the portion ofthe waveform to analyze for accurate distance measurement of the exampleobject 108. In the illustrated example, the example waveform analyzer306 identifies displacement of the example object 108 with 100micrometer (e.g., μm) precision. For example, the example third distance204 (FIG. 2) may only be 100 μm, which would otherwise be undetectedwithout the high resolution algorithm disclosed herein. While theaforementioned example discusses displacement, or amplitude (e.g.,distance), other characteristics of the example object 108 (e.g.,frequency, wavelength, height, phase, velocity, acceleration, etc.) canbe similarly determined. In the illustrated example, the examplewaveform analyzer 306 outputs the determined characteristic(s) (e.g.,distance, frequency, wavelength, height, phase, velocity, acceleration,etc.) to the example comparator 308.

The example comparator 308 receives the output of the example waveformanalyzer 306 and accesses the example characteristic database 312. Theexample comparator 308 searches example characteristic database 312 forcharacteristic(s) matching (e.g., substantially similar) to thedetermined characteristic(s) from the example waveform analyzer 306. Forexample, the example waveform analyzer 306 may have identified theexample object 108 has a displacement of 10 millimeters at a frequencyof 40 hertz. If such characteristics have previously been measured bythe example methods and apparatus disclosed herein, or otherwise storedin the example characteristic database 312, the example comparator 308identifies such characteristics in the characteristic database 312. Suchcharacteristics may additionally be associated with an identifier (e.g.,an identity of the object, a status of the object, etc.). The examplecomparator 308 outputs the determined characteristics and/or anyassociated identifier to the example reporter 314. In some examples, theexample comparator 308 outputs the determined characteristics to theexample signature associator 310.

The example signature associator 310 receives determined characteristicsfrom the example comparator 308. In the illustrated example, the examplesignature associator 310 receives such characteristics when the examplecomparator 308 does not identify matching characteristics in the examplecharacteristic database 312. The example signature associator 310identifies the determined characteristics as a signature of the exampleobject 108. The example signature associator 310 additionally associatesthe signature with an identity of the example object 108 (e.g., whatkind of object is the example object 108), a status of the exampleobject 108 (e.g., normal, abnormal, on, off, etc.), or other knownidentifier (e.g., vibration pattern associated with a person's voicereverberating off the example object 108, vibration pattern associatedwith a person's walking pattern on the example object 108, etc.). Insome examples, the example signature associator 310 associates a simpleidentifier, such as “known” (e.g., identifying that this particularcharacteristic or set of characteristics has previously beenidentified). In such examples, the example reporter 314 can identifywhen “unknown” (e.g., not previously identified) characteristics areidentified, as further discussed below. In the illustrated example, theexample signature associator 310 associates complex identifiers, such asspecific data about the example object 108. The specific data may bemanually identified by an operator of the example methods and apparatusdisclosed herein, loaded from a definition library of characteristics ofknown objects, or other know method of data entry. Additionally oralternatively, the specific data may be identified by searching anetwork (e.g., the Internet) for substantially similar characteristics.The example signature associator 310 outputs the determinedcharacteristics and any associated identifiers to at least one of theexample characteristic database 312 or the example reporter 314.

The example characteristic database 312 stores characteristicsassociated with signatures created by the example signature associator310 and/or characteristics associated with signatures retrieve fromthird party sources (e.g., the Internet, operator data entry, definitionlibrary, etc.). In the illustrated example, the example characteristicdatabase 312 is a storage device (e.g., a hard drive, solid state drive,floppy disk, compact disk, Blu-ray disk, RAID system, digital versatiledisk (DVD), etc.) disposed within the example controller 102.Alternatively, the example characteristic database 312 may be hostedand/or controlled by a third party (e.g., an external storage deviceconnectable through a network).

The example reporter 314 receives determined characteristics and/oridentifiers from at least one of the example comparator 308 or theexample signature associator 310. Based on the type of identifier, theexample reporter 314 reports an alert, a status, a description, or otherinformation associated with the determined characteristics andidentifiers.

For example, when first characteristics are associated with a firstidentifier indicating the example object 108 is operating normally, theexample reporter 314 reports a normal status for the example object 108.When second characteristics are associated with a second identifierindicating the example object 108 is not operating normally, the examplereporter 314 reports an abnormal status for the example object 108.Therefore, in such examples, the example methods and apparatus are afault detector, wherein the example reporter 314 reports possiblefaults, often before such faults become a much larger problem.

When third characteristics are associated with a third identifierindicating the example object 108 is not moving, the example reporter314 reports that the example object 108 is powered off. Therefore, insuch examples, the example reporter 314 reports on/off frequency, powerissues, power consumption, duty cycle, or other related power concerns.

When fourth characteristics are associated with a fourth identifierindicating known characteristics have been measured in association withthe example object 108, the example reporter 314 describes the knowncharacteristics. Therefore, in such examples, the example methods andapparatus are an identity detector, wherein the example reporter 314identifies and reports patterns associated with known objects, voices,walking patterns, and other vibration causing biometrics that arefrequently measured the example methods and apparatus disclosed herein.When fifth characteristics are associated with a fifth identifierindicating unknown characteristics have been measured in associationwith the example object 108, the example reporter 314 generates analert. Therefore, in such examples, the example methods and apparatusare a security system, wherein the example reporter 314 generates analert when unknown voices, walking patterns, etc. are identified.

FIG. 4 is a diagram illustrating an example operation 400 between theexample controller 102, the example transducer 104, and the exampleobject 108 of FIGS. 1-3. In operation, the example pulse generator 300(FIG. 3) generates one or more example bursts 402 a, 402 b, 402 c, 402 dof pulses prompting the example ultrasonic transducer 104 (FIGS. 1A-1B)to send ultrasonic waves towards the example object 108 (FIGS. 1A-1B).As illustrated in FIG. 4, the example object 108 has an oscillationdefined by at least example points 404 a, 404 b, 404 c, 404 d. Theultrasonic waves produced by the example ultrasonic transducer 104traverse a medium (e.g., the air) and are reflected off of the exampleobject 108 at example points 404 a, 404 b, 404 c, 404 d (e.g., exampleburst 402 a reflects off of the example object 108 at example point 404a, example burst 402 b reflects off of the example object 108 at examplepoint 404 b, example burst 402 c reflects off of the example object 108at example point 404 c, example burst 402 d reflects off of the exampleobject 108 at example point 404 d). The example pulse generator 300identifies receipt of reflected ultrasonic waves (e.g., example bursts402 a, 402 b, 402 c, 402 d returning to the example ultrasonictransducer 104) by the example ultrasonic transducer 104 at examplelocations 406 a, 406 b, 406 c, 406 d. In the illustrated example, thereflected example bursts 402 a, 402 b, 402 c, 402 d are converted froman analog signal to a digital signal (e.g., a constant “1” or high).

In the illustrated example, upon receipt of the example reflectedultrasonic waves (e.g., at example locations 406 a, 406 b), the examplewaveform generator 302 determines the time of flight (e.g., the timebetween sending an ultrasonic wave(s) toward an object and receiving areflected ultrasonic wave(s)) of the example bursts 402 a, 402 b.Subsequently, during periods 408, 410, the example waveform generator302 stores the time of flight for example bursts 402 a, 402 b, prior tothe example pulse generator transmitting example burst 402 c. Althoughthe illustrated example is described with reference to determining andstoring the time of flight for example bursts 402 a and 402 b, theprocess of sending pulses, receiving reflections, determining andstoring the time of flight may repeat for many iterations until enoughsample points are captured and stored to reconstruct a complete waveformof the example object 108.

In some examples, the example ultrasonic transducer 104 is stilloscillating due to receipt of reflected example burst 402 a when theexample pulse generator 300 transmits example burst 402 b (e.g., theultrasonic transducer 104 reverberates due to receipt of example burst402 a and is instructed to transmit example burst 402 b prior to thereverberations ceasing). For example, if the example object 108 isvibrating at 100 Hz, a sampling rate of 200 Hz may not provide enoughtime for the example ultrasonic transducer 104 to recover from exampleburst 402 a (e.g., stop oscillating from transmission and/or receipt ofprevious ultrasonic waves) before transmission of example burst 402 b.In such examples, the continuing reverberations may interfere withexample burst 402 b. Accordingly, the example pulse generator 300identifies whether the example ultrasonic transducer 104 isreverberating prior to transmitting example burst 402 b. In theillustrated example, the example pulse generator 300 transmits a seriesof pulses that are phase shifted at lower frequencies (e.g., lower thanthe frequencies sent during example burst 402 a) during the exampleburst 402 b. When the example ultrasonic transducer 104 receives exampleburst 402 b (e.g., the phase shifted lower frequency series of pulses),the example filter 304 distinguishes example burst 402 b fromoscillation due to example burst 402 a. The example waveform generator302 therefore obtains accurate data from both example burst 402 a andexample burst 402 b, even where interference between bursts wouldnormally occur.

In the illustrated example, the example waveform generator 302 storesdata from period 408 after the example pulse generator 300 identifiesreceipt of reflected ultrasonic waves by the example ultrasonictransducer 104 at example location 406 a and prior to the example pulsegenerator 300 transmitting example burst 402 b. In some examples, thetransmission of subsequent bursts (e.g., 402 b) is delayed until datafrom period 408 is stored. In some examples, the example pulse generator300 generates bursts at a fixed rate independent of whether data hasbeen stored by the example waveform generator 302. In such examples, theexample pulse generator 300 transmits a series of pulses that are phaseshifted at lower frequencies during the subsequent burst (e.g., 402 b).The sampling time varies depending on the vibration frequency of theexample object 108. For example, when the example object 108 isvibrating at a very low frequency, the example methods and apparatussample for a long time period, and when the example object 108 isvibrating at a high frequency, the example methods and apparatus samplefor a shorter time period. As noted above, the sampling frequency andphase may adapt as well.

After the example waveform generator 302 stores time of flight dataduring periods 408, 410, the example waveform generator 302 generatorsan example waveform during period 412 based on the data stored inperiods 408, 410. As illustrated in FIG. 4, only two periods 408, 410are depicted wherein the example waveform generator 302 stores data.However, any number of periods may be used to obtain additional samplepoints and achieve better resolution of the oscillations of the exampleobject 108.

After the example waveform generator 302 generates the example waveform,the example filter 304 applies one or more filters to the generatedwaveform to resolve ultrasonic signals from noise. Thereafter, theexample waveform analyzer 306 determines characteristics of the exampleobject 108 from the resolved waveform from the example filter 304. Theexample comparator 308 receives the output of the example waveformanalyzer 306 and accesses the example characteristic database 312 toidentify any known signatures associated with the characteristicsdetermined by the example waveform analyzer 306.

When no known signatures associated with the characteristics determinedby the example waveform analyzer 306 are located by the examplecomparator 308, the example signature associator 310 identifies thedetermined characteristics as a signature of the example object 108 andassociates the signature with an identity of the example object 108, astatus of the example object 108, or other known identifier. The examplecharacteristic database 312 stores characteristics associated withsignatures created by the example signature associator 310.

The example reporter 314 reports an alert, a status, a description, orother information associated with the determined characteristics andidentifiers. When one or more known signatures associated with thecharacteristics determined by the example waveform analyzer 306 arelocated by the example comparator 308, the example reporter 314 reportsa status, description, or identity associated with the signature. Whenno known signatures are located by the example comparator 308, theexample reporter 314 reports an alert, indicating unknowncharacteristics have been identified.

In some examples, the example comparator 308 identifies characteristicsin the example characteristic database 312 matching characteristics onlypartially measured by the example ultrasonic transducer 102 (e.g.,characteristics are matched prior to completion of a long sampleperiod). In such examples, the aforementioned process may be streamlinedto increase efficiency and decrease processing. Additionally, frequentlymeasured characteristics may be subject to the same streamlineprocessing. The streamline processing may be implemented by storing morefrequently detected characteristics in more easily accessible memory(e.g., cache memory), processing smaller wave functions (e.g., portionsof the generated waveform), or other streamline processes apparent toone of ordinary skill in the art.

While an example manner of implementing the example controller of FIGS.1A-1B is illustrated in FIG. 3, one or more of the elements, processesand/or devices illustrated in FIG. 3 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the example pulse generator 300, the example waveform generator302, the example filter 304, the example waveform analyzer 306, theexample comparator 308, the example signature associator 310, theexample characteristic database 312, the example reporter 314, theexample bus 316, and/or, more generally, the example controller 102 ofFIG. 3 may be implemented by hardware, software, firmware and/or anycombination of hardware, software and/or firmware. Thus, for example,any of the example pulse generator 300, the example waveform generator302, the example filter 304, the example waveform analyzer 306, theexample comparator 308, the example signature associator 310, theexample characteristic database 312, the example reporter 314, theexample bus 316, and/or, more generally, the example controller 102 ofFIG. 3 could be implemented by one or more analog or digital circuit(s),logic circuits, programmable processor(s), application specificintegrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s))and/or field programmable logic device(s) (FPLD(s)). When reading any ofthe apparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example pulsegenerator 300, the example waveform generator 302, the example filter304, the example waveform analyzer 306, the example comparator 308, theexample signature associator 310, the example characteristic database312, the example reporter 314, the example bus 316, and/or, moregenerally, the example controller 102 of FIG. 3 is/are hereby expresslydefined to include a tangible computer readable storage device orstorage disk such as a memory, a digital versatile disk (DVD), a compactdisk (CD), a Blu-ray disk, etc. storing the software and/or firmware.Further still, the example controller 102 of FIGS. 1-3 may include oneor more elements, processes and/or devices in addition to, or insteadof, those illustrated in FIG. 3, and/or may include more than one of anyor all of the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing the example controller 102 of FIG. 3 is shown in FIGS. 5-7.In this example, the machine readable instructions comprise a programfor execution by a processor such as the processor 8 shown in theexample processor platform 800 discussed below in connection with FIG.8. The program may be embodied in software stored on a tangible computerreadable storage medium such as a CD-ROM, a floppy disk, a hard drive, adigital versatile disk (DVD), a Blu-ray disk, or a memory associatedwith the processor 812, but the entire program and/or parts thereofcould alternatively be executed by a device other than the processor 812and/or embodied in firmware or dedicated hardware. Further, although theexample program is described with reference to the flowchart illustratedin FIGS. 5-7, many other methods of implementing the example controller102 may alternatively be used. For example, the order of execution ofthe blocks may be changed, and/or some of the blocks described may bechanged, eliminated, or combined.

As mentioned above, the example processes of FIGS. 5-7 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a tangible computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory(ROM), a compact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and transmission media. As usedherein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. Additionallyor alternatively, the example processes of FIGS. 5-7 may be implementedusing coded instructions (e.g., computer and/or machine readableinstructions) stored on a non-transitory computer and/or machinereadable medium such as a hard disk drive, a flash memory, a read-onlymemory, a compact disk, a digital versatile disk, a cache, arandom-access memory and/or any other storage device or storage disk inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, for brief instances, for temporarily buffering,and/or for caching of the information). As used herein, the termnon-transitory computer readable medium is expressly defined to includeany type of computer readable storage device and/or storage disk and toexclude propagating signals and transmission media. As used herein, whenthe phrase “at least” is used as the transition term in a preamble of aclaim, it is open-ended in the same manner as the term “comprising” isopen ended.

An example program 500 for measuring and analyzing vibration signaturesis illustrated in FIG. 5 and begins at block 502. At block 502, theexample pulse generator 300 (FIG. 3) instructs the example ultrasonictransducer 104 (FIGS. 1A-1B) to conduct distance measurements of theexample object 108 (FIGS. 1A-1B). The example waveform generator 302generates a waveform from the data collected by the example ultrasonictransducer 104 (block 504). The example filter 304 resolves thegenerated waveform to distinguish ultrasonic waves from noise or otherinterferences (block 506). The example waveform analyzer 306 determinesa first vibration characteristic (e.g., frequency (e.g., in Hz),amplitude (e.g., in mm), height (e.g., in mm), velocity (e.g., in mm/s),acceleration (e.g., in mm/s²), etc.) of the example object 108 from thefiltered waveform (block 508).

At block 510, the example comparator 308 identifies if a type (e.g.,frequency, amplitude, height, velocity, acceleration, etc.) of the firstvibration characteristic from block 508 exists in the examplecharacteristic database 312 (e.g., previously measured and stored,downloaded from a network, etc.). If the example comparator 308identifies the vibration characteristic type is not in the examplecharacteristic database 312 (block 510: NO), then the example signatureassociator 310 associates an “unknown” identifier (e.g., an indicatorthat this characteristic has not yet been measured) with the firstvibration characteristic (block 512). In the illustrated example, theexample “unknown” identifier indicates the example object 108 isdisplaying the first vibration characteristic for the first time.Control proceeds to block 524.

If the example comparator 308 identifies the vibration characteristictype is in the example characteristic database 312 (block 510: YES),then the example comparator 308 determines if the first vibrationcharacteristic (from block 508) conflicts with a stored characteristicof the same type (e.g., a frequency characteristic for the exampleobject 108 has previously been identified and stored) (block 514). Ifthe example comparator 308 identifies that the first vibrationcharacteristic conflicts with a stored characteristic of the same type(e.g., a first frequency is stored in the example characteristicdatabase 312 and the first vibration characteristic is a secondfrequency different from the first frequency) (block 514: YES), then theexample signature associator 310 associates an “abnormal” identifier(e.g., an indicator that the first vibration characteristic is differentfrom previously identified characteristics) with the first vibrationcharacteristic (block 516). In the illustrated example, the example“abnormal” identifier indicates the example object 108 is operating inan inconsistent manner. Control proceeds to block 524.

The example “abnormal” identifier may indicate the example object 108 isfailing, faulty, or going to fail. Alternatively, the abnormalidentifier may indicate the example object 108 is turned off.Alternatively, the abnormal identifier may indicate a new signaturecharacteristic of the example object 108 (e.g., a second object causingthe example object 108 to act abnormally). In some examples, additionalinformation is added to the example “abnormal” identifier by an operatorof the example controller 102 or identified in a definition library ofvibration characteristics. For example, when the example signatureassociator 310 associates an “abnormal” identifier to the firstvibration characteristic and the operator knows that the first vibrationcharacteristic is associated with a person's voice reverberating off ofthe example object 108 (e.g., during a vocal experiment), the operatorcan manually associate the abnormal identifier with a particularperson's voice pattern. Similarly, a person's walking pattern (e.g., aperson causes a unique vibration pattern when walking across the exampleobject 108) can be associated with the “abnormal identifier.” In thismanner, the example characteristic database 312 is filled with uniqueidentification information for people, objects, or the like byassociating vibration characteristics with an abnormal identifier uniqueto the person and/or object. Alternatively, such vibrationcharacteristics (e.g., voice patterns, walking patterns, objectinteraction patterns, etc.) may be stored in a definition libraryaccessible by the example controller 102.

If the example comparator 308 identifies that the first vibrationcharacteristic does not conflict with a stored characteristic of thesame type (block 514: NO), then the example comparator 308 determines ifthe first vibration characteristic has been measured (e.g., identified,determined, etc.) a threshold amount of times (block 518). The thresholdmay be set to any threshold such that consistent vibrationcharacteristic patterns emerge. If the example comparator 308 determinesthat the first vibration characteristic has been measured a thresholdamount of times (block 518: YES), then the example signature associator310 associates a “normal” identifier with the first vibrationcharacteristic (block 520). In the illustrated example, the example“normal” identifier indicates the example object 108 is operating in aconsistent manner (e.g., similar vibration characteristics have beenmeasured for the threshold amount of times). Control proceeds to block524.

In some examples, additional information is added to the example“normal” identifier by an operator of the example controller 102 or isstored in a definition library to further distinguish normal operatingconditions. For example, “normal” operation may be associated withparticular vibration characteristics (e.g., the example object 108 isnormally turned on, the example object 108 has a signature frequency,etc.). In such examples, the “abnormal” identifier would conversely beassociated with any vibration characteristic different from theparticular vibration characteristics (e.g., the example object 108 thatis normally on is now displaying no vibration characteristics (e.g.,powered off), the example object 108 is no longer displaying thesignature frequency, etc.).

Alternatively, normal operation may be associated with no vibrationcharacteristics at all (e.g., the example object 108 is normally turnedoff (e.g., inactive), the example object 108 is the ground and has nomeasurable vibration characteristics under normal conditions, etc.). Insuch examples, the “abnormal” identifier would conversely be associatedwith any vibration characteristic (e.g., the example object that isnormally off is now displaying vibration characteristics (e.g. poweredon), the example object 108 is the ground and vibrating due to peoplewalking on it, an earthquake, other objects contacting or falling ontothe example object 108, etc.).

If the example comparator 308 determines that the first vibrationcharacteristic has not been measured a threshold amount of times (block518: NO), then the example signature associator 310 associates a “known”identifier with the vibration characteristic (block 522). In theillustrated example, the example “known” identifier indicates theexample object 108 is redisplaying the first vibration characteristic.However, because the example comparator 308 determined that the firstvibration characteristic has not been measured a threshold amount oftimes, the signature associator 310 increments a count of the number oftimes the first vibration characteristic has been measured (e.g.,increments the number of times the signature associator 310 has handledthe first vibration characteristic) (block 526). Control proceeds toblock 524.

After the example signature associator 310 associates an identifier(e.g., known (block 522), unknown (block 512), normal (block 520),abnormal (block 516), etc.) with the first vibration characteristic, theexample signature associator 310 stores the first vibrationcharacteristic and any associated identifier as a signaturecharacteristic of the example object 108 (block 524).

The example signature associator 310 additionally associates the firstvibration characteristic with any additional vibration characteristicsassociated with the example object 108 that are stored in the examplecharacteristic database 312. For example, the example signatureassociator 310 aggregates other vibration signature characteristicsassociated with the example object 108 together to identify the exampleobject 108 by its signature characteristics. The aggregation ofsignature characteristics make up a signature profile (e.g., consistingof numerous signature characteristics) of the example object 108.

The example waveform analyzer 306 determines if there are additionalvibration characteristics of the example object 108 different from thefirst vibration characteristic (block 528). If the example waveformanalyzer 306 identifies additional vibration characteristics (block 528:YES), control returns to block 508. If the example waveform analyzer 306identifies no additional vibration characteristics (block 528: NO), theexample program 500 ceases.

An example program 600 for measuring and analyzing vibration signaturesis illustrated in FIG. 6 and begins at block 602. At block 602, theexample pulse generator 300 (FIG. 3) instructs the example ultrasonictransducer 104 (FIGS. 1A-1B) to conduct distance measurements of theexample object 108 (FIGS. 1A-1B). The example waveform generator 302generates a waveform from the data collected by the example ultrasonictransducer 104 (block 604). The example filter 304 resolves thegenerated waveform to distinguish ultrasonic waves from noise or otherinterferences (block 606). The example waveform analyzer 306 determinesa second vibration characteristic (e.g., frequency (e.g., in Hz),amplitude (e.g., in mm), height (e.g., in mm), velocity (e.g., in mm/s),acceleration (e.g., in mm/s²), etc.) of the example object 108 from thefiltered waveform (block 608).

At block 610, the example comparator 308 identifies if the secondvibration characteristic (e.g., frequency, amplitude, height, velocity,acceleration, etc.) is associated with a signature characteristic storedin the example characteristic database 312 (e.g., previously measuredand stored, downloaded from a network, identified in a definitionlibrary, etc.). If the example comparator 308 identifies the secondvibration characteristic is associated with a signature characteristicstored in the example characteristic database 312 (block 610: YES), thenthe example reporter 314 reports the signature characteristic and/or anyassociated identifier (block 612).

For example, the example reporter 312 reports known and/or normalcharacteristics. Known characteristics include characteristicsassociated with particular object identities (e.g., voice recognition,walking pattern recognition, and object recognition based on definitionlibraries, operator input during tests, etc.). Normal characteristicsinclude a particular characteristic or set of characteristics (e.g., afrequency of 29 Hz and an amplitude of 13 mm, a frequency of 0 Hz and anamplitude of 0 mm, etc.) consistently measured by the example methodsand apparatus disclosed herein.

If the example comparator 308 identifies the second vibrationcharacteristic is not associated with a signature characteristic storedin the example characteristic database 312 (block 610: NO), then theexample reporter 314 generates an alert indicating unknown and/orabnormal characteristics have been identified. Unknown characteristicsinclude characteristics not previously identified or stored in adefinition library. Abnormal characteristics include characteristicsthat conflict with normal characteristics. Thereafter, the exampleprogram 600 ceases.

In the illustrated example, the example program 500 and the exampleprogram 600 are executed in parallel, such that as the signatureassociator 310 is determining what identifier to associate with a givencharacteristics, the example reporter 314 is reporting and/or generatingalerts in response to identifier type (e.g., alert for unknown and/orabnormal characteristics, report for known and/or normalcharacteristics, etc.). Alternatively, the example program 600 may beran after running the example program 500.

FIG. 7 is a flow chart illustrating an example implementation of blocks506 and 606. The example implementation of block 506 and 606 starts atblock 700. At block 700, the example filter 304 receives a time domainwaveform characterizing the example object 108 from the example waveformgenerator 302. In the illustrated example, the example filter 304bandpass filters the generated waveform to keep certain frequencies(e.g., within a passband) and exclude other frequencies (block 702). Theexample filter 304 performs a FIR Hilbert transform on the filteredwaveform to shift the phase (block 704). The example filter 304envelopes the generated waveform (block 706).

In the illustrated example, the example waveform analyzer 306 determinesa maximum amplitude of the enveloped waveform (block 708). Thereafter,the example waveform analyzer 306 identifies a first time point relatedto the generated waveform (block 710). The example waveform analyzer 306determines if, at the first time point, the envelope amplitude isgreater than half of the maximum amplitude (block 712). If the examplewaveform analyzer 306 determines, at the first time point, that theenvelope amplitude is greater than half of the maximum amplitude (block712: YES), control proceeds to block 714. Otherwise (block 712: NO),control returns to block 710.

At block 714, the example waveform analyzer 306 identifies a thresholdamount of additional time points (e.g., 10) surrounding the first timepoint. Thereafter, the example waveform generator 302 creates a phasedomain waveform based on the threshold amount of additional time pointsand the example waveform analyzer 306 performs linear regression on thethreshold amount of additional time points (block 716). The examplewaveform analyzer 306 identifies a zero-crossing nearest the time point(block 718). At the nearest zero-crossing, the example waveform analyzeridentifies the subwavelength resolution of the example object 108 (block720). Thereafter, the example implementation of blocks 506 and 606ceases.

FIG. 8 is a block diagram of an example processor platform 800 capableof executing the instructions of FIGS. 5-7 to implement the examplecontroller 102 of FIGS. 1-3. The processor platform 800 can be, forexample, a microprocessor, a server, a personal computer, a mobiledevice (e.g., a cell phone, a smart phone, a tablet such as an iPad™,etc.), a personal digital assistant (PDA), an Internet appliance, or anyother type of computing device.

The processor platform 800 of the illustrated example includes aprocessor 812. The processor 812 of the illustrated example is hardware.For example, the processor 812 can be implemented by one or moreintegrated circuits, logic circuits, microprocessors or controllers fromany desired family or manufacturer.

The processor 812 of the illustrated example includes a local memory 813(e.g., a cache). The processor 812 of the illustrated example is incommunication with a main memory including a volatile memory 814 and anon-volatile memory 816 via a bus 818. The volatile memory 814 may beimplemented by Synchronous Dynamic Random Access Memory (SDRAM), DynamicRandom Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)and/or any other type of random access memory device. The non-volatilememory 816 may be implemented by flash memory and/or any other desiredtype of memory device. Access to the main memory 814, 816 is controlledby a memory controller.

The processor 812 further includes the example pulse generator 300, theexample waveform generator 302, the example filter 304, the examplewaveform analyzer 306, the example comparator 308, the example signatureassociator 310, and the example reporter 314.

The processor platform 800 of the illustrated example also includes aninterface circuit 820. The interface circuit 820 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 822 are connectedto the interface circuit 820. The input device(s) 822 permit(s) a userto enter data and commands into the processor 812. The input device(s)can be implemented by, for example, an audio sensor, a microphone, acamera (still or video), a keyboard, a button, a mouse, a touchscreen, atrack-pad, a trackball, isopoint and/or a voice recognition system.

One or more output devices 824 are also connected to the interfacecircuit 820 of the illustrated example. The output devices 1024 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a light emitting diode (LED), a printer and/or speakers).The interface circuit 820 of the illustrated example, thus, typicallyincludes a graphics driver card, a graphics driver chip or a graphicsdriver processor.

The interface circuit 820 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) via a network826 (e.g., an Ethernet connection, a digital subscriber line (DSL), atelephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 800 of the illustrated example also includes oneor more mass storage devices 828 for storing software and/or data.Examples of such mass storage devices 828 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, RAIDsystems, and digital versatile disk (DVD) drives. The one or more massstorage devices 828 include the example characteristic database 312.

The coded instructions 832 of FIGS. 5-7 may be stored in the massstorage device 828, in the volatile memory 814, in the non-volatilememory 816, and/or on a removable tangible computer readable storagemedium such as a CD or DVD.

From the foregoing, it will be appreciate that the disclosed methods,apparatus, and articles of manufacture provide off-device vibrationmeasurement and analysis using ultrasonic transducers to detectsubwavelength vibration characteristics. The disclosed methods,apparatus, and articles of manufacture are not subject to thesubstantial wear, contaminants, moving parts, and volatile environmentsto which on-device vibration methods and apparatus are subjected, adaptto varying temperatures, and provide increased resolution in thecharacteristics measured.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. A meter, comprising: an ultrasonic transducer togenerate an emission at a first frequency; a waveform generator togenerate a waveform representing periodic vibration of an object at asecond frequency different from the first frequency based on a first setof distance measurements between the ultrasonic transducer of the meterand the object; a waveform analyzer to determine a first vibrationcharacteristic of the object based on the waveform; a comparator tocompare the first vibration characteristic of the object to a signaturevibration characteristic of the object; and a reporter to generate analert, in response to determining that the first vibrationcharacteristic of the object does not match the signature vibrationcharacteristic of the object.
 2. The meter of claim 1, wherein the firstvibration characteristic is at least one of the second frequency, anamplitude, a height, a velocity, or an acceleration of the periodicvibration.
 3. The meter of claim 1, wherein the first set of distancemeasurements between the ultrasonic transducer and the object areobtained by the ultrasonic transducer using a sampling window having aduration that is inversely proportional to the second frequency of theperiodic vibration of the object.
 4. The meter of claim 1, wherein thefirst frequency of the ultrasonic transducer is at least 40 kilohertz.5. The meter of claim 1, wherein the ultrasonic transducer is a firstultrasonic transducer configured to obtain the first set of distancemeasurements from a first surface of the object, further including asecond ultrasonic transducer in communication with a bus, the secondultrasonic transducer configured to obtain a second set of distancemeasurements between the second ultrasonic transducer and a secondsurface of the object.
 6. The meter of claim 1, wherein the object is afirst object, further including a signature associator to associate thefirst vibration characteristic with at least one of an abnormalcharacteristic of the first object, an inactive characteristic of thefirst object, or a signature vibration characteristic of a secondobject, the second object causing the first object to present the firstvibration characteristic.
 7. The meter of claim 1, wherein the object isa first object, the alert is to indicate at least one of an abnormalcharacteristic of the first object, an inactive characteristic of thefirst object, a previously undetected characteristic of the firstobject, or a signature vibration characteristic of a second object, thesecond object causing the first object to present the first vibrationcharacteristic.
 8. The meter of claim 1, further including a signatureassociator to store the first vibration characteristic as a signaturevibration characteristic of a second object, the second object causingthe object to present the first vibration characteristic.
 9. The meterof claim 1, wherein the comparator is to identify a walking pattern ofan individual based on the first vibration characteristic, the firstvibration characteristic associated with vibrations caused by theindividual walking on the object.
 10. The meter of claim 1, wherein thewaveform analyzer is to: determine a maximum amplitude of the first setof distance measurements; determine a time where an amplitude of thewaveform is greater than half the maximum amplitude; perform phaselinear regression on multiple points around the time; determine anearest zero crossing based on the multiple points; and determine a subwavelength resolution based on the nearest zero crossing.
 11. The meterof claim 1, wherein the waveform analyzer is to: determine an amplitudeof the waveform; determine a velocity of the waveform based on theamplitude; and determine an acceleration of the waveform based on thevelocity.
 12. The meter of claim 1, wherein the first set of distancemeasurements is distributed over a plurality of periods of the periodicvibration.
 13. The meter of claim 1, wherein the waveform generator isto generate the waveform as a summation of sinusoidal waves.
 14. Amethod, comprising: obtaining, via an ultrasonic transducer operating ata first frequency, a first set of distance measurements between theultrasonic transducer and an object; generating, via a processor, awaveform based on the first set of distance measurements representingperiodic vibration of the object at a second frequency different fromthe first frequency; determining, via the processor, a first vibrationcharacteristic of the object based on the waveform; comparing, via theprocessor, the first vibration characteristic of the object to asignature vibration characteristic of the object; and generating, viathe processor, an alert, in response to determining that the firstvibration characteristic of the object does not match the signaturevibration characteristic of the object.
 15. The method of claim 14,wherein the first vibration characteristic is at least one of the secondfrequency, an amplitude, a height, a velocity, or an acceleration. 16.The method of claim 14, wherein the first set of distance measurementsbetween the ultrasonic transducer and the object are obtained using asampling window having a duration that is inversely proportional to thesecond frequency of the periodic vibration of the object.
 17. The methodof claim 14, wherein the first set of distance measurements are relativeto a first surface of the object, further including obtaining a secondset of distance measurements between a second ultrasonic transducer anda second surface of the object.
 18. The method of claim 14, wherein theobject is a first object, further including associating the firstvibration characteristic with at least one of an abnormal characteristicof the first object, an inactive characteristic of the first object, ora signature vibration characteristic of a second object, the secondobject causing the first object to present the first vibrationcharacteristic.
 19. The method of claim 14, wherein the object is afirst object, the alert indicative of at least one of an abnormalcharacteristic of the first object, an inactive characteristic of thefirst object, or a signature vibration characteristic of a secondobject, the second object causing the first object to present the firstvibration characteristic.
 20. The method of claim 14, further includingstoring the first vibration characteristic as a signature vibrationcharacteristic of a second object, the second object causing the objectto present the first vibration characteristic.
 21. The method of claim14, further including resolving the waveform by removing noise measuredby the ultrasonic transducer.
 22. The method of claim 14, furtherincluding identifying a walking pattern of an individual based on thefirst vibration characteristic, the first vibration characteristicassociated with vibrations caused by the individual walking on theobject.
 23. The method of claim 14, further including: determining amaximum amplitude of the first set of distance measurements; determininga time where an amplitude of the waveform is greater than half themaximum amplitude; performing phase linear regression on multiple pointsaround the time; determining a nearest zero crossing based on themultiple points; and determining a sub wavelength resolution based onthe nearest zero crossing.
 24. The method of claim 14, furtherincluding: determining an amplitude of the waveform; determining avelocity of the waveform based on the amplitude; and determining anacceleration of the waveform based on the velocity.
 25. A meter,comprising: an ultrasonic transceiver connected to an amplifier circuit,the ultrasonic transceiver to produce a wave at a first frequency toobtain first set of distance measurements between the ultrasonictransceiver and an object and convert the first set of distancemeasurements into a signal that represents periodic vibration of theobject at a second frequency that is different from the first frequency,the amplifier circuit to receive the signal from the ultrasonictransceiver and amplify the signal, to generate an amplified signal; afilter circuit connected to the amplifier circuit, the filter circuit toreceive the amplified signal from the amplifier circuit and filter theamplified signal, to generate a filtered amplified signal; and acontroller connected to the filter circuit, the controller to: analyzethe filtered amplified signal from the filter circuit; determinecharacteristics of the filtered amplified signal, to generate determinedcharacteristics; and generate an alert, in response to determining thatthe determined characteristics do not match characteristics stored in adatabase.